Dias Kadyrbayev and Azamat Tazhayakov, both 19, were also indicted by a federal grand jury of ‘conspiracy to obstruct justice’ and ‘obstructing justice with intent to impede the Boston Marathon bombing investigation’, said the US Attorney's office for Massachusett on Thursday.

Indictment precedes trial and, if convicted, the two face up to 20 years in prison on the obstruction of justice count and up to five years in prison on the conspiracy count, as well as a fine of $250,000 dollars. Both also face the possibility of being deported, reported a news agency.

Kadyrbayev and Tazhayakov were detained and originally charged in May for conspiracy to obstruct justice. They are now also accused of obstructing justice and aiding and abetting. Prosecutors alleged that the two young men and another conspirator worked together April 18 to retrieve accused bomber Dzhokhar Tsarnaev's laptop computer and backpack containing fireworks from his dormitory room.

Prosecutors said that after discussing what to do, the pair put the backpack in a garbage bag and placed it in a dumpster. The next morning, after Dzhokhar was identified as one of the bomibing suspects, Kadyrbayev and Tazhayakov watched as a garbage truck came to their apartment complex and emptied the contents.

The FBI later found the backpack in a landfill in New Bedford, Massachusetts, where the two men were living on student visas. The FBI identified two brothers, 26-year-old Tamerlan Tsarnaev and 19-year-old Dzhokar Tsarnaev, as suspects behind the Boston bombings which killed three and wounded over 200 in April.

Tamerlan died after a shootout with the police four days after the bombing while Dzhokar was apprehended in a suburb of Boston following massive manhunt by law enforcement authorities. Dzhokhar Tsarnaev made his first public appearance in court in July and pleaded not guilty to 30 charges for his alleged role in the Boston Marathon bombings.